The present invention is concerned with boat trailers of the type used to support and transport recreational boats and cruisers, and more particularly to a trailer having improved frame structure characteristics which permit the trailer to be readily and rapidly prefitted to the boat to be transported in a manner to provide a precise boat-trailer match-up. This matching of the trailer supports, whether of the bunk and roller combination or the all roller style, to the hull configuration, greatly enhances the safety with which the boats can be loaded to, and off-loaded from, the trailer, and with which they are transported.
While, in the past, boat trailers have provided cross frame supports for rigidly connecting the side booms of the trailer frame, and have provided for some pivot of the cross members, and while cross members have also been longitudinally movable to predetermined locations on the side rail or boom members, via the expedient of providing a series of bolt openings, for instance, on the side booms to which the cross rail members could be selectively attached, it has not been possible, in boat trailer frame structures with which I am familiar, to achieve precise longitudinal movement of the boat hull supporting cross frame members, while still providing the pivoting action required.